Atomic and nuclear collisions for materials analysis

The irradiation of all materials with charged particles leads to an ionization and consequently to emission of characteristic X-rays. The technique using this phenomenon induced by protons or other heavier projectiles is called PIXE. In principle, the analysis of all the elements may be performed, but, practically, only elements with an atomic weight greater than 25 may be quantitatively determined. The characteristic K X-rays of light elements are indeed so highly absorbed in the sample that corrections cannot be made to obtain a sufficient accuracy with PIXE. Elements with an atomic weight lower than 25 are more accurately analysed by detection of gamma-rays (PIGE) or charged particles ejected by the interaction between the incident light projectile and the nucleus. Another way to achieve quantitative analysis of these layers is to use the spectroscopy of elastically backscattered particles: RBS (Rutherford Backscattering Spectroscopy).